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A Frog is a Frog, No Matter How Small

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Our friend Horton said it first – Dr. Seuss himself would be impressed with the latest discovery of the world’s smallest vertebrate.

This tiny frog, only 7.7 millimeters long, was recently discovered in an eastern New Guinea rainforest.It's smaller than a peanut - two or three of these critters could fit comfortably on a dime!

I wondered how being such a little guy could be advantageous for a frog.Perhaps he’s just an evolutionary outlier who has survived despite the odds.But the researchers explain that eleven different populations of frogs have independently evolved to be smaller than 13 millimeters. This suggests that these frogs are not outliers at all, but have evolved to occupy a particular ecological niche on the wet leafy floor of the rainforest.

Reading about this frog reminded me of an epic cinematic performance starring Frog’s best friend Toad. The pebble toad from Venezuela appears in the BBC series Life, and if you haven’t seen this video it’s certainly worth three minutes of your time (in fact, the whole series is incredible).

When this brave little toad is confronted with a predator it curls up into a ball, tenses its muscles, and then hurls itself down the side of a mountain, bouncing off the rocks masquerading as a dislodged pebble to escape predators. The pebble toad is only a few centimeters in length, and is small and light enough that when his muscles are tensed the forces of impact he experiences when careening down the mountain are too small to cause him any harm. He lives on table-topped mountains that rise out of the rainforest in South America. This isolated environment has caused many of the animals that live there to evolve differently, including the pebble toad, which unlike other toads is barely able to hop an inch and is a poor swimmer. Some pebble toads drown if they accidentally land their mountain dive in a deep puddle, but this is rare, and is a risk you have to be willing to take when faced with a giant toad-hungry tarantula.

These are two Seuss-worthy examples of evolution at its finest, filling the niches with adorable peanut-sized frogs and daredevil toads.

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